Interpretive Summary: We provide a framework for explaining four different forms of desertification, including vegetation loss due to agriculture, vegetation loss due to changes in climate or land use, invasion of woody vegetation into perennial grasslands, and invasion of exotic grasses into desert shrublands resulting in replacement of woody vegetation. Our framework is based on changes in the length of connected pathways for the movement of fire, water, and soil resources. Biophysical feedbacks that increase the length of pathways can explain the persistence of desertified landscapes around the globe. Management of connectivity is essential to understanbding and potentially reversing desertification.

Technical Abstract:
Desertification, broad-scale land degradation in drylands, is a major environmental hazard facing inhabitants of the world’s deserts as well as an important component of global change. There is no unifying framework that simply and effectively explains different forms of desertification. Here we argue for the unifying concept that diverse forms of desertification, and its remediation, are driven by changes in the length of connected pathways for the movement of fire, water and soil resources. Biophysical feedbacks exist that increase the length of connected pathways explaining the persistence of desertified landscapes around the globe. Management of connectivity in the context of environmental and socioeconomic change is essential to understand, and potentially reverse, the harmful effects of desertification.